Large Area Self-Powered Al-ZnO/(n)Si Hetero-Junction Photodetectors With High Responsivity

Al-ZnO/Si heterojunction-based large area, selfpowered, low reverse leakage current, and broadband photodetectors with high responsivity are fabricated using the simple and low temperature process. Different from widely applied (p)Si-based heterojunctions, these devices are (n)Si-based and offer superior performance. With optimized Al-ZnO thickness, excellent light confinement is achieved. An interfacial passivation layer that improves the hetero-interface helps achieved a reverse current density as low as 4.5 × 10 ^-7 A/cm ^-2 at -0.5 V for a 4.84 cm ² device, with rectification ratio of 2.7 × 10 ³ at ±0.5 V. In self-powered mode, the photodetector achieved responsivities of 0.292, 0.426, and 0.486 A/W (external quantum efficiency, EQE of 78.7%, 96.1%, and 98.8%) for primary blue (460 nm), green (550 nm), and red (610 nm) light, respectively. The operation of self-powered Al-ZnO/(n)Si photodetectors is demonstrated for the first time with modulated optical signal at circuit level.